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The cumulative error can be found by rolling the gear to be tested with a master gear, f o r which purpose the total composite error of the master gear must be known and, where necessary, deducted from the teet result.

DIN ENG_图文_百度文库

They a r e intended t o serve t h e designer as a check l i s t of a l l the points which must dij taken i n t o account when choosing a gear f i t. The tolerances and allowances etated’in the following Tables apply to gears according to D M Sheet 1, Section 2. In this case the permissible radial eccentricity for the tip circle should be taken from Table 3. Measuring plane perpendicular with centre distance line 6 Tolerances f o r uear assemblies.

The reference diameter to which the axial eccentricity is related is found as: Base tanuent lenRth allowancea; dual cone width allowances; Dem. They should be taken from the Tables i n Section 6 t o s u i t the gear f i t selected grade dinn tolerance zone. For grades P 8 it is recommended that the tip cylinder should be used for setting up the gear blank, or that test flanges should be provided.

If the c h a r t feed i s operated and a t ra c e drawn corresponding t o t he upper and lower allowance, two concentric c i r c l e s a r e obtained if the recording i a made in pol ar Co-ordinates dih Figure 5 and two p a r a l l e l s t r a i g h t lines i f the recording i s made i n rectangular Co-ordinates see Figure 6.

For gears not covered i n the scope it may be necessary i certain circumstances to modify the n allowances and tolerances. dln

The c e n tre distance a” i s then reduced each time by the upper and louer allowance of the base tangent length converted t o the r a d i a l direction. Permissible radial eccentricits for tip cylinder when this is n o t used for settinn UE Table 4 Permissible radial eccentricity f o r. In connection v i t h the s e l e c t i o n of b a l l b e d n g e i t should be noted t h a t the tolerance allowed f o r t he bearing bores Q i n t h e housing r e l a t i v e t o the tolerance on t he centre distance Ta must be reduced by the amount of the r a d i a l run-out of the b a l l bearing outer ringe frL.

The ideal involute surface corresponding to the nominal dimension and shown in Figure 4 is outside the boundary involutes because of the negative base tangent length allowances see a l s o DIN Sheet IFigure I. The uncertainty i n measurement due t o var i at i on of the measuring Observance of t h e s p e c i fi e d allowances may be determined d i r e c te.

The cumulative error of a tooth system is the common and simultaneous effect of a number of individual errors on the ideal position and geometry of the tooth flanks. Minor var iat i o n s may, however, a r i s e in 584405 connection because the individual allowances have been rounded t o preferred numbers.

The centre distance a” can be s e t by placing the appropriate s l i p gauges between t he two mounting a rb o rs or the individual arbors. In the came of instrument drives it is recommended, particularly when mounted overhung, that ball bearings with increased radial clearance ehould be used and proloading applied.

The face alignment error is designated as pos i t i ve if t he var 5405 at i on i s i n the right-hand dir e c t i o nand negative i f i t i a i n dun left-hand di r ect i on with reference t o the design value n of the h e l i x angle Bo. I n t h e case of housings made of aluminium a l l o y s and s i m i l a r materials, s u i t a b l e measues should be taken, e. The t o t a l composite error according t o Section 4. The values specified relate to the bearing when inetalled. These allowances, together with the centre distance allowances, are the criteria for a gear fit.

This i s performed a s follows: The following are distinguished: In t h i s connection i t should be noted i n p a r t i c u l a r t h a ti n the case of disc-shaped 558405 blanks i n which t h e length of bore dih a not s u f f i c i e n t t o support the gear blank during the gear-cutting procese, the end faces serve ae contact faces during the gear-cutting process and hence t h e i r geometrical and position var i at i ons determine t he qual i t y of th e tooth system.